Add a warning to the app:check-code if the version is missing

core/command/app/checkcode.php

@@ -131,6 +131,10 @@ class CheckCode extends Command {
 				}
 			});
 
+			$infoChecker->listen('InfoChecker', 'missingRequirement', function($minMax) use ($output) {
+				$output->writeln("<comment>ownCloud $minMax version requirement missing (will be an error in ownCloud 11 and later)</comment>");
+			});
+
 			$infoChecker->listen('InfoChecker', 'duplicateRequirement', function($minMax) use ($output) {
 				$output->writeln("<error>Duplicate $minMax ownCloud version requirement found</error>");
 			});

lib/private/app/codechecker/infochecker.php

@@ -83,13 +83,18 @@ class InfoChecker extends BasicEmitter {
 				'type' => 'duplicateRequirement',
 				'field' => 'min',
 			];
+		} else if (!isset($info['dependencies']['owncloud']['@attributes']['min-version'])) {
+			$this->emit('InfoChecker', 'missingRequirement', ['min']);
 		}
+
 		if (isset($info['dependencies']['owncloud']['@attributes']['max-version']) && $info['requiremax']) {
 			$this->emit('InfoChecker', 'duplicateRequirement', ['max']);
 			$errors[] = [
 				'type' => 'duplicateRequirement',
 				'field' => 'max',
 			];
+		} else if (!isset($info['dependencies']['owncloud']['@attributes']['max-version'])) {
+			$this->emit('InfoChecker', 'missingRequirement', ['max']);
 		}
 
 		foreach ($info as $key => $value) {